One example of a conventional laser mask marker of the above described type includes a fixed mask having a plurality of different fixed patterns on a surface thereof, a XY deflector disposed on the laser beam incident side of the fixed mask for illuminating a laser beam to a desired fixed pattern, and a XY deflector disposed on the laser beam emerging side of the fixed mask for illuminating the laser beam which has passed through the desired pattern to a desired position on a work, and performs synthetic printing of adequately combined fixed patterns on a large area of the work without shifting the work (see Japanese Patent Laid Open No. 2-15887).
In another example of such a conventional laser mask marker, an entire pattern is divided into a plurality of divided pattern portions, the divided pattern portions are displayed on a liquid crystal mask on a time division basis, and synthetic printing is performed on a work by shifting the work in one direction each time a laser beam is illuminated on the liquid crystal mask (see Japanese Patent Laid Open No. 2-187287).
Other laser mask markers are disclosed in, for example, Japanese Patent Laid Open No. 2-268988).
In recent years, there has been a demand for a YAG laser mask marker which can adequately and instantaneously change a pattern, including complicated and desired characters, symbols, figures and patterns, on a work made of a metal, resin, ceramic, paper or cloth, and which can perform clear, high speed printing over a large area without moving the work during printing and without generating variations using a small laser oscillator.
The aforementioned conventional laser mask markers cannot meet such a demand due to the following drawbacks.
In the laser mask marker disclosed in Japanese Patent Laid Open No. 2-15887, when a pattern other than the plurality of fixed patterns on the fixed mask is to be printed, the fixed mask must be replaced with another one. Also, the XY deflector disposed on the laser beam incident side is considered to be used only for selective illumination of the fixed pattern and not for raster scanning. That is, the illumination of the laser beam conducted by the XY deflector is considered batch illumination of the fixed pattern with an enlarged laser beam. Thus, although this structure is advantageous in that synthetic printing can be conducted on a large area without shifting the work during printing, a complicated and desired pattern cannot be suitably and instantaneously changed, as clear, high speed printing which is free from variations cannot be conducted using a small laser oscillator.
The laser mask marker disclosed in Japanese Patent Laid Open No. 2-187287 is an epoch making marker in terms of the display of the entire pattern on the liquid crystal mask on a time division basis. In this laser mask marker, a complicated pattern can be suitably and instantaneously changed, and synthetic printing can be performed on a large area. However, since the work is synchronously moved each time the laser beam is illuminated, clear, high speed printing free from variations cannot be performed without moving the work during printing using a small laser oscillator. The laser mask marker disclosed in Japanese Patent Laid Open No. 2-268988 suffers from the same problem.